This invention is concerned with a system or device for increasing the traction and braking capacity of a wheel on a rail while reducing the energy consumed by the wheel per unit load and simultaneously helping to maintain the rail crown profile.
There is a great need in the railroad industry to pull long and heavy trains with as few tractive units as possible. The locomotives or other tractive units used have been made heavy and with high powered diesel/electric or all electric drive systems to increase their tractive capability. The weight per axle has already been increased to a limiting capability of the tracks. Further increase in the power of the plant on board will not increase the tractive capability of the locomotive unless the wheel-rail contact conditions are improved. The adhesion/creepage characteristics of the contact shown in FIG. 1 (for clean, dry laboratory conditions 10, typical low contamination rail 11, and moderate contamination rail 12) make it clear that great improvements in adhesion levels are possible when the rail is cleaned. Furthermore, a cleaner rail surface leads to reduced creepages which lead to reduction of energy loss of a tractive contact.
Most of the improvements in modern locomotion to date have been internal to the engine. Not much has been done externally to improve the wheel-rail contact conditions. The approaches used to date include: (1) the application of sand, and (2) a special creepage control system used on the driving axles. Sand usage is very bad for the rail and wheel, as well as the locomotive bearings. Sand should be avoided as much as possible. It fouls up the track, wears out the rail and wheel at a very fast rate and reduces engine life. Creepage control is good, but it can run into problems when the rail is intermittently excessively contaminated. In the future it is expected that rails will be even more contaminated due to increased rail lubrication by railroad companies for reducing fuel consumption. Thus, what is urgently needed is an external system that will prepare the rail crown for high adhesion capability before the wheel rolls on it.
Another problem that has developed in the last few decades is the flattening of the rail head crown in a short period of service, due to considerably increased axle loads needed on modern freight trains. A damaged rail crown leads to bad car dynamics, poor ride quality and damaged freight. The progressive railroad companies tackle the problem by grinding the rail crown to restore profile and/or by using head-hardened or high-strength alloy rails. Both choices add considerably to track maintenance costs. It will therefore be very helpful economically to the railroads if the system used to prepare the rail crown for the train also helps to maintain the proper rail crown curvature. A system which will prepare the rail surface and help maintain the curvature of its crown would benefit all locomotion (diesel/electric as well as all electric) and provide better rail economics with improved profits. In the area of locomotion, it will especially benefit the creepage control systems by enabling them to operate continually in a stable, high adhesion zone. The present invention provides a solution to all three problem areas discussed above. It will improve adhesion, reduce creepage and related contact energy loss, and help to maintain rail crown profile.